There are numerous causes of intoeing in children, including metatarsus adductus, clubfeet, and internal tibial torsion. The device of the present invention is designed specifically for the treatment of metatarsus adductus only.
Metatarsus adductus is a congenital condition in which the forefoot is adducted or turned in relativeto the hindfoot or heel. The primary treatment is corrective casting, which gives excellent results. However, it has serious disadvantages, including repeated expensive castings, skin pressure problems, and potentially diastrous vascular problems.
Alternatives to casting have been sought over the years, and they basically fall into two groups: shoes (or boots) and braces (or splints). In spite of several introductions over the years, these alternatives have not been utilized to any significant degree, and casting remains even today the treatment of choice. The reason is that these alternatives lack the features that enable them to correct the deformity.
Shoes and boots have been ineffective in obtaining correction because, being all enclosing, they do not provide enough pressure at specific points to effect correction. At the present time shoes are used mainly as a holding device after correction has been obtained with casts.
The braces and splints that have been introduced so far do not hold the heel and the medial portion of the foot securely enough to allow for successful correction of the deformity; for example, U.S. Pat. Nos. 3,924,615 to McKim; 3,812,850 and 3,910,267 to Reiman; and the brace designed by Lusskin as reported in The Journal of Bone and Joint Surgery, January 1951, p. 269. All these devices use straps to hold the medial portion of the foot, which is insufficient for correction.
U.S. Pat. No. 3,973,559 to Reiman attempts to address the problem by adding a wall along the medial side of the footplate. This patent is believed to be the closest prior art. However, it still does not hold the medial portion of the foot securely enough to effect correctoion, and lacks several important features that determine success or failure:
(1) The medial wall extends only to the base of the big toe, and depends on the child wearing both footplates attached together in an angular relationship, and the child lying prone (on his stomach), and the mattress on which the child lies, to effect correction of the bit toe varus, which is an important component of the deformity. Hence, the splint has cumbersome constraints of wearing both footplates even if only one foot is affected, and of posture since the child has to be lying prone.
(2) The medial wall does not have an upper ledge to prevent dorsal migration of the big toe and medial portion of the forefoot, thus escaping from the corrective influence of the medial wall. This is very important if one realizes how wiggly the infant foot can be.
(3) The medial wall is straight. This is much less effective than a slightly convex border (abducted position) which allows the foot to be placed in a slightly over-corrected position.
(4) The splint does not have rigid support for the lateral aspect of the heel to prevent valgus (turning out) of the heel, a complication to be avoided in the treatment of metatarsus adductus.